Vatican Museum archaeologists will unveil a necropolis next month, including a section discovered three years ago during the construction of a parking lot in Vatican City.

The Vatican Museums said the dig had revealed several burial structures and sarcophagi, along with tomb decorations including frescoes, mosaic floors, and inscriptions. Most of the tombs are well-preserved and date from between the era of Augustus (23 B.C. to 14 A.D.) to Constantine (306-337), reported The Associated Press.

Guided visits to the newly discovered necropolis will be part of celebrations to mark the 500th anniversary of the Vatican Museums.

The Vatican has said the necropolis is only second in importance to the one underneath St. Peter's Basilica.